The overall objectives of the project are: 1) to isolate and characterize a growth factor produced by plerocercoids of the tapeworm, Spirometra mansonoides; 2) to establish the biochemical and physiological relationships of the plerocercoid growth factor (PGF) to known growth factors such as somatotropin, prolactin and insulin and to lesser known growth factors, somatomedin and epidermal growth factor; 3) to determine the effects of purified preparations of PGF on larger mammals, especially primates. Preliminary data with a radioreceptor assay using cultured human lymphocytes have shown that PGF competes for binding sites in a system which has been reported to bind only human growth hormone or closely related human hormones, such as prolactin or chorionic somatomammotropin. PGF also works similarly to growth hormone in a radioreceptor assay employing liver microsomes from pregnant rabbits. Therefore, it is conceivable that PGF might have biological activity in humans. More specifically, it is planned to: 1) establish and employ the radioreceptor assays for PGF activity; 2) continue our efforts to obtain a "pure" preparation of PGF from plerocercoid incubation media; 3) pursue the observation that liver glycogen concentrations are higher in plerocercoid-infected rats than in controls; 3) investigate the effects of PGF on other aspects of mammalian metabolism, especially lipid metabolism; 5) test the effects of PGF in larger animals, particularly in primates.